/Engine/Plugins/2D/Paper2D/Source/Paper2DEditor/Public/PaperJSONHelpers.h
Returns the bool named Key or bDefaultIfMissing if it is missing or the wrong type (note: no way to determine errors!)
static bool ReadBoolean ( const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< class [FJsonObject](API\Runtime\Json\Dom\FJsonObject) > Item, const [FString](API\Runtime\Core\Containers\FString) & Key, bool bDefaultIfMissing )